Prognostic role of serum prostatic acid phosphatase for 103Pd-based radiation for prostatic carcinoma

Kinetic Studies of Newly Patented Aminoalkanol Derivatives with Potential Anticancer Activity as Competitive Inhibitors of Prostate Acid Phosphatase

BACKGROUND

Acid phosphatase and its regulation are important objects of biological and clinical research and play an important role in the development and treatment of prostate and bone diseases. The newly patented aminoalkanol (4-[2-hydroxy-3-(propan-2-ylamino)propyl]-1,7-dimethyl-8,9-diphenyl-4-azatricyclo[5.2.1.02,6]dec-8-ene-3,5,10-trione hydrochloride) (I) and (4-[3-(dimethylamino)-2-hydroxypropyl]-1,7-dimethyl-8,9-diphenyl-4-azatricyclo[5.2.1.02,6]dec-8-ene-3,5,10-trione hydrochloride) (II) derivatives have potential anticancer activity, and their influence on enzymatic activity can significantly impact the therapeutic effects of acid phosphatase against many diseases. Therefore, in this study, we investigated the action of compounds (I) and (II) on acid phosphatase.

METHODS

Capillary electrophoresis was used to evaluate the inhibition of acid phosphatase. Lineweaver-Burk plots were constructed to compare the Km of this enzyme in the presence of inhibitors (I) or (II) with the Km in solutions without these inhibitors.

RESULTS

Compound (I) showed a stronger competitive inhibition against acid phosphatase, whereas derivative (II) showed a weaker competitive type of inhibition. The detailed kinetic studies of these compounds showed that their type and strength of inhibition as well as affinity depend on the kind of substituent occurring in the main chemical molecule.

CONCLUSIONS

This study is of great importance because the disclosed inhibition of acid phosphatase by compounds (I) and (II) raises the question of whether these compounds could have any effect on the treatment possibilities of prostate diseases.

Detecting acid phosphatase enzymatic activity with phenol as a chemical exchange saturation transfer magnetic resonance imaging contrast agent (PhenolCEST MRI)

Phenol contains an exchangeable hydroxyl proton resonant at 4.8 ppm from the resonance frequency of water in the 1H nuclear magnetic resonance (1H NMR) spectrum, enabling itself to be detected at sub-mM concentration by either chemical exchange saturation transfer magnetic resonance imaging (CEST MRI) or exchange-based T2 relaxation enhancement (T2ex) effect under acidic and basic conditions, respectively. We recently investigated the T2ex effects of phenol and its derivatives, but the CEST characteristics of phenols are unknown in detail, and no study on using the natural CEST MRI effects of phenol for detecting enzymatic activity has been conducted. Herein, on the basis of the inherent CEST MR property of phenol, namely phenolCEST, we developed the first MRI approach to detect acid phosphatase (AcP) enzymatic activity. Upon the activity of AcP at pH = 5.0, non-CEST-detectable enzyme substrate phenyl phosphate was converted to CEST-detectable phenol, providing a simple way to quantify AcP activity directly without the need for a second signalling probe. We showed the application of this phenolCEST biosensor for measuring AcP activity in both enzyme solutions and cell lysates of prostate cells. This work opens a door for the utilization of phenolCEST MRI technique in sensor design and development.

Loss of prostatic acid phosphatase and α-synuclein cause motor circuit degeneration without altering cerebellar patterning

Prostatic acid phosphatase (PAP), which is secreted by prostate, increases in some diseases such as prostate cancer. PAP is also present in the central nervous system. In this study we reveal that α-synuclein (Snca) gene is co-deleted/mutated in PAP null mouse. It is indicated that mice deficient in transmembrane PAP display neurological alterations. By using immunohistochemistry, cerebellar cortical neurons and zone and stripes pattern were studied in Pap^{-/- ;}Snca^-/- mouse cerebellum. We show that the Pap^{-/- ;}Snca^-/- cerebellar cortex development appears to be normal. Compartmentation genes expression such as zebrin II, HSP25, and P75NTR show the zone and stripe phenotype characteristic of the normal cerebellum. These data indicate that although aggregation of PAP and SNCA causes severe neurodegenerative diseases, PAP^-/- with absence of the Snca does not appear to interrupt the cerebellar architecture development and zone and stripe pattern formation. These findings question the physiological and pathological role of SNCA and PAP during cerebellar development or suggest existence of the possible compensatory mechanisms in the absence of these genes.

Long-term outcomes for patients with prostate cancer having intermediate and high-risk disease, treated with combination external beam irradiation and brachytherapy

Background. Perception remains that brachytherapy-based regimens are inappropriate for patients having increased risk of extracapsular extension (ECE). Methods. 321 consecutive intermediate and high-risk disease patients were treated between 1/92 and 2/97 by one author (M. Dattoli) and stratified by NCCN guidelines. 157 had intermediate-risk; 164 had high-risk disease. All were treated using the combination EBRT/brachytherapy ± hormones. Biochemical failure was defined using PSA >0.2 and nadir +2 at last followup. Nonfailing patients followup was median 10.5 years. Both biochemical data and original biopsy slides were independently rereviewed at an outside institution. Results. Overall actuarial freedom from biochemical progression at 16 years was 82% (89% intermediate, 74% high-risk) with failure predictors: Gleason score (P = .01) and PSA (P = .03). Hormonal therapy did not affect failure rates (P = .14). Conclusion. This study helps to strengthen the rationale for brachytherapy-based regimens as being both durable and desirable treatment options for such patients. Prospective studies are justified to confirm these positive results.

The histidine phosphatase superfamily: structure and function

The histidine phosphatase superfamily is a large functionally diverse group of proteins. They share a conserved catalytic core centred on a histidine which becomes phosphorylated during the course of the reaction. Although the superfamily is overwhelmingly composed of phosphatases, the earliest known and arguably best-studied member is dPGM (cofactor-dependent phosphoglycerate mutase). The superfamily contains two branches sharing very limited sequence similarity: the first containing dPGM, fructose-2,6-bisphosphatase, PhoE, SixA, TIGAR [TP53 (tumour protein 53)-induced glycolysis and apoptosis regulator], Sts-1 and many other activities, and the second, smaller, branch composed mainly of acid phosphatases and phytases. Human representatives of both branches are of considerable medical interest, and various parasites contain superfamily members whose inhibition might have therapeutic value. Additionally, several phosphatases, notably the phytases, have current or potential applications in agriculture. The present review aims to draw together what is known about structure and function in the superfamily. With the benefit of an expanding set of histidine phosphatase superfamily structures, a clearer picture of the conserved elements is obtained, along with, conversely, a view of the sometimes surprising variation in substrate-binding and proton donor residues across the superfamily. This analysis should contribute to correcting a history of over- and mis-annotation in the superfamily, but also suggests that structural knowledge, from models or experimental structures, in conjunction with experimental assays, will prove vital for the future description of function in the superfamily.

Long-term outcomes after treatment with brachytherapy and supplemental conformal radiation for prostate cancer patients having intermediate and high-risk features

BACKGROUND

This study summarizes long-term outcomes from treatment of prostate cancer with increased risk of extracapsular cancer extension (ECE) using brachytherapy-based treatment.

METHODS

A total of 282 consecutive patients were treated from 1992-1996 by 1 author (M.D.). Two hundred forty-three patients had at least 1 higher risk feature for ECE including Gleason Score 7-10 (172), prostate-specific antigen (PSA) above 10 (166), and clinical stages T(2c) (109) and T(3) (107). Using National Comprehensive Cancer Network (NCCN) guidelines, 119 patients had intermediate-risk disease and 124 had high-risk disease. Patients received pelvic 3-dimensional conformal external beam radiation followed by a palladium (Pd)-103 boost. Generous brachytherapy margins were utilized. Biochemical failure was defined using ASTRO Consensus Definition, nadir +2 and PSA >0.2 ng/mL at last follow-up. The nonfailing patient follow-up period was 1-14 years (median, 9.5 years). Biochemical data and original biopsy slides were independently re-reviewed at the University of Washington (by K.W. and L.T., respectively).

RESULTS

Overall actuarial freedom from biochemical progression at 14 years was 81%, including 87% and 72% having intermediate and high-risk disease, respectively. Absolute risk of failure decreased progressively, falling to 1% beyond 6 years after treatment. All failing patients had prostate biopsies without evidence of local recurrence. The strongest predictor of failure was Gleason score (P = .03) followed by PSA (P = .041). Treatment morbidity was limited to temporary RTOG grade 1-2 urinary and gastrointestinal symptoms.

CONCLUSIONS

High tumor control rates are possible with beam radiation followed by Pd-103 brachytherapy. Despite perceptions that brachytherapy is inappropriate for patients at higher risk for ECE, this series strengthens the rationale that brachytherapy-based treatment may be a desirable modality for such patients.

15-Year biochemical relapse free survival in clinical Stage T1-T3 prostate cancer following combined external beam radiotherapy and brachytherapy; Seattle experience

PURPOSE

Long-term biochemical relapse-free survival (BRFS) rates in patients with clinical Stages T1-T3 prostate cancer continue to be scrutinized after treatment with external beam radiation therapy and brachytherapy.

METHODS AND MATERIALS

We report 15-year BRFS rates on 223 patients with clinically localized prostate cancer that were consecutively treated with I(125) or Pd (103) brachytherapy after 45-Gy neoadjuvant EBRT. Multivariate regression analysis was used to create a pretreatment clinical prognostic risk model using a modified American Society for Therapeutic Radiology and Oncology consensus definition (two consecutive serum prostate-specific antigen rises) as the outcome. Gleason scoring was performed by the pathologists at a community hospital. Time to biochemical failure was calculated and compared by using Kaplan-Meier plots.

RESULTS

Fifteen-year BRFS for the entire treatment group was 74%. BRFS using the Memorial Sloan-Kettering risk cohort analysis (95% confidence interval): low risk, 88%, intermediate risk 80%, and high risk 53%. Grouping by the risk classification described by D'Amico, the BRFS was: low risk 85.8%, intermediate risk 80.3%, and high risk 67.8% (p = 0.002).

CONCLUSIONS

I(125) or Pd(103) brachytherapy combined with supplemental EBRT results in excellent 15-year biochemical control. Different risk group classification schemes lead to different BRFS results in the high-risk group cohorts.

What constitutes high-risk locally advanced prostate cancer?

Excluding basal and squamous cell cancers of the skin, prostate cancer is the most common malignancy diagnosed in the United States. With increasing awareness and routine prostate-specific antigen testing, a remarkable migration in the clinical presentation of the disease has occurred in the past 20 years. An increasingly greater proportion of men are diagnosed with clinically organ-confined disease. In parallel, the incidence of men presenting with clinically bulky locoregional or metastatic disease has decreased. Despite the stage migration, when clinical and pathologic parameters are taken into account, a significant number of men with clinically localized prostate cancer do not have truly organ-confined disease. Such men might not to be cured with single modality, locally directed therapies. Thus, prostate cancer represents a disease spectrum with a number of biologic and clinical factors determining disease extent. An overview of some of these aspects of the disease is presented.

High-dose-rate intensity-modulated brachytherapy with external beam radiotherapy for prostate cancer: California endocurietherapy’s 10-year results

PURPOSE

To present the long-term outcome and morbidity of high-dose-rate brachytherapy (HDR-BT) combined with external beam radiotherapy (EBRT) for localized prostate cancer.

METHODS AND MATERIALS

Between September 1991 and December 1998, 209 consecutive patients with no prior androgen suppression were treated with HDR-BT plus EBRT. The median follow-up was 7.25 years (range, 5-12 years). The patients were stratified into three risk groups: low (Stage T2a or less, Gleason score </=6, and prostate-specific antigen [PSA] level </=10 ng/mL), intermediate (Stage T2b,c, Gleason score 7, and PSA level 10-20 ng/mL), and high (Stage T3, Gleason score 8-10, and PSA level >20). Four definitions of PSA progression were compared with the general clinical failure outcome: the American Society for Therapeutic Radiology and Oncology (ASTRO) definition, nadir plus 2.0 ng/mL, two consecutive rises >/=0.5 ng/mL, and PSA level >0.2 ng/mL. Morbidity was scored using Radiation Therapy Oncology Group criteria.

RESULTS

The general clinical control rate was 90% (188 of 209), and the general clinical failure rate was 10% (21 of 209). The overall survival rate was 79%, and the cause-specific survival rate was 97%. The PSA progression-free survival (ASTRO definition) rate was 90%, 87%, and 69% for the low-, intermediate-, and high-risk groups, respectively. The nadir plus 2 ng/mL and two rises >/=0.5 definitions correlated better with the actual clinical outcome than did the ASTRO and PSA >0.2 ng/mL definitions. The rate of Grade 3 and 4 late urinary morbidity was 6.7% and 1%, respectively, mostly occurring in patients who had undergone post-RT transurethral prostate resection. No late Grade 3 or 4 rectal morbidity developed. The sexual potency preservation rate was 67%.

CONCLUSION

Our 10-year results have demonstrated HDR-BT plus EBRT is a proven treatment for all stages of localized prostate cancer. The morbidity was low, but post-RT transurethral resection should be avoided.

Permanent Interstitial Brachytherapy for Clinically Organ-Confined High-Grade Prostate Cancer With a Pretreatment PSA < 20 ng/mL

The objective of this study was to determine the effect of biopsy Gleason score 8 and 9 histology on biochemical outcome following a permanent prostate brachytherapy approach that includes multiple periprostatic seeds and supplemental external beam radiation. Forty-six consecutive T1c-T2b (1997 AJCC) patients with Gleason score 8 and 9 prostate cancer who were either hormone naive (33 patients) or received cytoreductive (< or =6 months) hormonal therapy (13 patients) underwent brachytherapy from June 1995 to November 2000. The median patient age was 69.7 years, with a median pretreatment prostate-specific antigen (PSA) of 7.7 ng/mL. The median follow-up was 58 months (range 27-93 months). Forty-five of the patients were implanted with Pd-103 and 44 received supplemental external beam radiation therapy (45 Gy). Biochemical success was defined by either a PSA < or = 0.4 ng/mL after a nadir or by the ASTRO consensus definition. The actuarial 7-year biochemical disease-free survival was 84.8% using either a PSA < or = 0.4 ng/mL or the ASTRO consensus definition. The median postimplant PSA was less than 0.1 ng/mL for both the hormone naive and hormonally manipulated patients. The utilization of hormonal therapy for 6 months or less duration resulted in a statistically nonsignificant improvement in biochemical outcome (92.3% versus 81.8%, P = 0.393). When stratified by pretreatment PSA, 87.9% of patients with a pretreatment PSA < or = 10 ng/mL and 76.9% with a pretreatment PSA > 10 ng/mL (P = 0.377) remained biochemically free of disease. In multivariate analysis, none of the clinical, treatment, or dosimetric parameters predicted for outcome. Following a permanent prostate brachytherapy approach that used multiple periprostatic seeds, the majority of patients with clinically organ-confined Gleason score 8 and 9 prostate cancer remain biochemically free of disease with identical outcomes for both biochemical definitions of success.

Ten-year biochemical relapse-free survival after external beam radiation and brachytherapy for localized prostate cancer: the Seattle experience

PURPOSE

The role of external beam radiation therapy in addition to brachytherapy continues to be scrutinized for long term control of PSA levels after prostate cancer diagnosis.

METHODS AND MATERIALS

We report 10-year biochemical relapse-free survival (BRFS) on 232 patients presenting with localized prostate cancer and consecutively treated with iodine(125) (I(125)) or palladium(103) (Pd(103)) brachytherapy and neoadjuvant external beam radiation therapy. Multivariate regression analysis was used to create a pretreatment clinical prognostic risk model using a modified ASTRO consensus definition (two consecutive rises in serum PSA) as the outcome. Gleason scoring was performed by pathologists at a small community hospital. Derived risk categories are the following: low = PSA <or=10 ng/mL, Gleason sum score <7, and stage <T2c; intermediate = PSA >10 ng/mL or Gleason Score >or=7 or stage >or=T2c (1 intermediate risk factor); and high = 2 or more intermediate risk factors. Time to PSA failure (local, distant, or biochemical) was calculated and compared using Kaplan-Meier plots.

RESULTS

Ten-year BRFS for the entire treatment group was 70%. Biochemical control rates by risk cohort analysis (95% confidence interval): low risk, 85% (83.3-90.7%); intermediate risk, 77% (73.0-84.5%); and high risk, 45% (45.4-57.2%). Using a risk grouping proposed by the Mt. Sinai group, the BRFS was: low risk, 84%; intermediate risk, 93%; and high risk, 57%. Grouping by the risk classification used by D'Amico, the BRFS was: low risk, 86%; intermediate risk, 90%; and high risk, 48%.

CONCLUSIONS

I(125) or Pd(103) brachytherapy, as a boost combined with EBRT, continues to result in high rates of biochemical control at 10 years. Different risk group classification schemes lead to different BRFS results.

Permanent Prostate Brachytherapy in Men with Clinically Localised Prostate Cancer

Permanent prostate brachytherapy techniques are associated with excellent biochemical control for patients with localised prostate cancer. Ten-year data show that permanent prostate brachytherapy is compatible with external beam irradiation or radical prostatectomy. However, treatment protocols and techniques for prostate brachytherapy vary between centres and there is little conformity of treatment protocols. The selection of patients for monotherapy or combined external beam irradiation and brachytherapy is controversial. The role of neoadjuvant androgen deprivation also remains unanswered in patients with localised prostate cancer. In addition, post-implant dosimetry may in fact be more significant for predicting outcome than the addition of adjuvant therapies, and should be a requirement when performing prostate brachytherapy. Data now seem to support specific computed tomography (CT)-based criteria to evaluate implant quality and delivered dose to the prostate. Unfortunately, prostate oedema and poor imaging techniques are limiting factors for evaluating implant dosimetry. Treatment planning techniques that use new treatment planning computers may assist in improving the implant procedure and dosimetry and are now available.

Permanent interstitial brachytherapy for the management of carcinoma of the prostate gland

PURPOSE

We summarize the permanent prostate brachytherapy literature, including biochemical outcomes, quality of life parameters and areas of controversy.

MATERIALS AND METHODS

The permanent prostate brachytherapy literature was reviewed using MEDLINE searches to ensure completeness.

RESULTS

Using various planning and intraoperative techniques the majority of the brachytherapy literature demonstrates durable biochemical outcomes for patients with low, intermediate and high risk features. For low risk patients there is no advantage to combining supplemental external beam radiation therapy with brachytherapy. In addition, supplemental external beam radiation therapy may not improve biochemical outcomes for patients at intermediate and high risk if the target volume consists of the prostate with a generous periprostatic margin. There is no defined role for adjuvant hormonal manipulation. Although a reliable set of pretreatment criteria to predict implant related morbidity is not available, severe urinary and rectal morbidity is rare. The incidence of brachytherapy induced erectile dysfunction is significantly greater than initially reported but the majority of patients respond favorably to sildenafil.

CONCLUSIONS

Continued refinements in brachytherapy planning and implementation techniques, postimplantation evaluation and continued elucidation of the etiology of urinary, bowel and sexual dysfunction should result in further improvements in biochemical and quality of life outcomes.

Long-term outcomes after treatment with external beam radiation therapy and palladium 103 for patients with higher risk prostate carcinoma: influence of prostatic acid phosphatase

BACKGROUND

The objective of this study was to define the long-term prognostic significance of prostatic acid phosphatase (PAP) levels in patients with higher risk, early-stage prostate carcinoma.

METHODS

One hundred sixty-one consecutive patients with Stage T1-T3 prostate carcinoma (according to the 1992 criteria of the American Joint Committee on Cancer) were treated from 1992 through 1996. Each patient had a Gleason score > or = 7 and/or a prostate specific antigen (PSA) level > 10 ng/mL. The original biopsy slides for 130 of 161 patients were retrieved and rereviewed by a single pathologist (L.T.). Enzymatic PAP measurements were determined using a standard method. Values up to 2.5 Units were considered normal. Patients received 41 grays (Gy) of external beam radiation therapy to a limited pelvic field followed 4 weeks later by a palladium 103 (Pd-103) boost using transrectal ultrasound and fluoroscopic guidance as described previously. The prescribed minimum Pd-103 dose to the prostate was 80 Gy (pre-National Institute of Standards and Technology [NIST]-99). Freedom from biochemical failure was defined as a serum PSA level < or =0.2 ng/mL at last follow-up.

RESULTS

There was little correlation between pretreatment PSA levels, Gleason scores, and PAP measurements. Thirty-eight patients developed biochemical failure. The overall actuarial freedom from biochemical progression at 10 years is 79%, with 118 patients followed for > 5 years. In a multivariate Cox proportional hazards analysis that considered each factor as a continuous variable, the strongest predictor of failure was PAP (P = 0.0001), followed by Gleason score (P = 0.13), and PSA (P = 0.04). PAP was especially helpful in stratifying patients with pretreatment PSA levels between 4 ng/mL and 20 ng/mL, for whom the prognosis does not different when they are subdivided into PSA categories. When the PAP subgroup analysis was limited to this relatively favorable group, there was a wide range of prognoses.

CONCLUSIONS

The biochemical cure rate was remarkably high among the 161 patients evaluated. The fact that the PAP was the strongest predictor of long-term biochemical failure in patients with otherwise higher risk features reported here suggests that it may be a more accurate indicator of micrometastatic disease compared with the Gleason score and the PSA level. This report adds to the rationale for reintroducing PAP measurement into general practice.

Does hormonal manipulation in conjunction with permanent interstitial brachytherapy, with or without supplemental external beam irradiation, improve the biochemical outcome for men with intermediate or high-risk prostate cancer?

OBJECTIVE

To determine whether hormonal manipulation improves the biochemical outcome for men with intermediate or high-risk prostate cancer and undergoing permanent brachytherapy with or without supplemental external beam radiation therapy.

PATIENTS AND METHODS

From April 1995 to August 2000, 350 patients with intermediate-risk (225 men; a Gleason score of >or= 7 or a prostate specific antigen, PSA, level of >or= 10 ng/mL or clinical stage >or= T2b) or high-risk features (125 men; two or three of a Gleason score of >or= 7 or PSA >or= 10 ng/mL or clinical stage >or= T2b) underwent transperineal ultrasonography-guided permanent brachytherapy. No patient underwent pathological lymph node staging. Of these patients, 293 received supplemental external beam radiation therapy (EBRT), 141 received hormonal manipulation, with 82 having hormonal therapy for <or= 4 months (median 4) for cytoreduction, while 59 had neoadjuvant and adjuvant hormonal manipulation (median 8 and 12 months for intermediate- and high-risk, respectively). The median patient age was 68.5 years. No patient was lost to follow-up. The mean (sd) and median follow-up was 50 (18) and 49 months (calculated from the day of implantation). Biochemical disease-free (BDF) survival was defined using a consensus definition. The clinical variables evaluated for BDF survival included risk group, Gleason score, patient age, clinical T-stage and pretreatment PSA. Treatment variables included use of hormonal manipulation stratified into cytoreductive (<or= 4 months) vs adjuvant (> 4 months) regimens, supplemental EBRT, isotope and dosimetric variables.

RESULTS

For intermediate-risk patients, the 6-year actuarial BDF survival rates were 98%, 96% and 100% for hormone naïve, cytoreductive and adjuvant treatment, respectively (P = 0.693); for high-risk patients the respective values were 79%, 94% and 92% (P = 0.046). When stratified by pretreatment PSA, hormonal manipulation improved the outcome for patients with a PSA of >or= 10 ng/mL (P = 0.019), but not for those with < 10 ng/mL (P = 0.661). Hormonal status was not statistically significant in predicting biochemical outcome when stratified by Gleason score. The follow-up in hormone-naïve patients was significantly longer than that in hormonally manipulated patients, at 55 (20) vs 43 (15) months (P < 0.001). In a multivariate analysis only the Gleason score predicted failure in intermediate-risk patients, while pretreatment PSA, the use of hormonal manipulation and Gleason score predicted the outcome in high-risk patients (P = 0.035). For both hormone-naïve and hormonally manipulated BDF patients, the median PSA level after implantation was < 0.1 ng/mL.

CONCLUSION

In patients treated by permanent prostate brachytherapy, hormonal manipulation improved the biochemical outcome for those at high-risk and those with an initial PSA of >or= 10 ng/mL, but not for those with intermediate-risk features. The use of hormonal therapy for> 4 months conferred no additional biochemical advantage over short-course regimens. Because the follow-up in hormone-naïve patients was longer than that for those receiving hormonal manipulation, additional follow-up will be mandatory to confirm the durability of these findings.

Treatment outcomes and quality-of-life issues for patients treated with prostate brachytherapy

The increasing popularity of brachytherapy for treatment of early-stage prostate cancer requires oncology nurses to have a comprehensive knowledge of the disease, its treatment, and management of side effects. Because quality-of-life (QOL) issues have become an important consideration in treatment selection for many patients, oncology nurses must have a thorough understanding of these QOL issues and their management. Armed with knowledge about prostate brachytherapy and its effect on QOL, oncology nurses can offer accurate information and evidence-based symptom management techniques to patients undergoing brachytherapy for prostate cancer.

Risk group stratification in patients undergoing permanent (125)I prostate brachytherapy as monotherapy

PURPOSE

Patients undergoing prostate brachytherapy (PB) as monotherapy are often selected on the basis of favorable pretreatment factors. However, intermediate and high-risk prostate cancer patients are commonly offered PB as monotherapy without the addition of external beam radiotherapy (EBRT) or hormonal therapy. This series reports the outcome of patients undergoing PB as monotherapy who were stratified into low, intermediate, and high-risk groups with extended follow-up.

METHODS AND MATERIALS

A total of 102 patients with clinically localized prostate cancer underwent PB alone as monotherapy. EBRT or hormonal therapy was not part of their initial treatment. Prostate-specific antigen (PSA) relapse-free survival (PRFS) was determined in accordance with the American Society for Therapeutic Radiology and Oncology consensus statement. Patients were stratified as at favorable risk (Stage T1-2a, pretreatment PSA < or =10.0 ng/mL, and Gleason score < or =6), intermediate risk (one prognostic indicator with a higher value), or unfavorable risk (> or =2 indicators with higher values). The median follow-up period for patients in this series was 7 years (range 2.1-9.7). The median age at treatment was 71 years (range 54-80), and the median prescribed dose of (125)I was 145 Gy.

RESULTS

Forty patients experienced a biochemical relapse at a median of 1.9 years (range 0.4-4.2). The 5-year actuarial PRFS rate for patients with favorable, intermediate, and unfavorable risk was 85%, 63%, and 24%, respectively (p <0.0001). All but 1 patient had the relapse within the first 5 years of treatment. When stratifying patients on the basis of their pretreatment PSA level, the 5-year PRFS rate for men with a PSA < or =10 ng/mL vs. >10 ng/mL was 78% vs. 35%, respectively (p = 0.0005). Furthermore, the 5-year PRFS rate for men with a Gleason score of < or =6 vs. > or =7 was 74% vs. 33%, respectively (p = 0.0001). No difference was found between Stage T1-T2a and Stage T2b or higher (64% vs. 54%, respectively; p = 0.353).

CONCLUSION

On the basis of risk stratification, PB as monotherapy produces comparable PRFS to EBRT and surgery at 7 years of follow-up. PB as monotherapy is particularly ineffective in patients with unfavorable risk factors, and additional therapy is warranted.

Biochemical outcome for hormone-naïve patients with high-risk prostate cancer managed with permanent interstitial brachytherapy and supplemental external-beam radiation

PURPOSE

The purpose of this article is to report the 5-year biochemical disease-free outcome for hormone-naive patients with high-risk disease who underwent permanent prostate brachytherapy. Multiple clinical and treatment parameters were also evaluated to determine whether any of these influence biochemical outcome.

MATERIALS AND METHODS

Sixty-six hormone-naïve patients underwent transperineal ultrasound-guided permanent prostate brachytherapy with generous periprostatic margins by use of either 103Pd or 125I for high-risk prostate cancer from April 1995 to October 1999. High-risk patients presented with two or three of the following risk factors: Gleason score > or = 7, prostate-specific antigen > or = 10 ng/mL, and clinical stage > or = T2b, 1997 AJCC. No patient underwent pathological lymph node staging. Only one patient was implanted with monotherapy, whereas 65 patients received supplemental external-beam radiation therapy before a prostate brachytherapy boost. The median patient age was 69 years (range, 50-81 years). No patient was lost to follow-up. The mean follow-up and median follow-up were 53.2 +/- 14.9 months and 53.7 months, respectively (range, 19.8-79.7 months). Follow-up was calculated from the day of implantation. Biochemical disease-free survival was defined by the American Society of Therapeutic Radiology and Oncology consensus definition. Clinical parameters evaluated for biochemical disease-free survival included patient age, clinical stage, Gleason score, and pretreatment prostate-specific antigen. Treatment parameters included use of supplemental external-beam radiation therapy and choice of isotope.

RESULTS

The 5-year actuarial biochemical disease-free survival rate was 79.9%. In multivariate analysis, preimplantation prostate-specific antigen (P = 0.008) was the only clinical or treatment parameter that predicted for biochemical failure. The mean and median posttreatment prostate-specific antigen levels were 0.13 +/- 0.22 ng/mL and < 0.1 ng/mL, respectively.

DISCUSSION

At a median follow-up of 53.7 months, hormone-naive patients with high-risk disease who undergo permanent prostate brachytherapy have a high probability of 5-year biochemical disease-free survival and an apparent plateau on the biochemical disease-free survival curve.

Acid phosphatases

Acid phosphatases (APs) are a family of enzymes that are widespread in nature, and can be found in many animal and plant species. Mystery surrounds the precise functional role of these molecular facilitators, despite much research. Yet, paradoxically, human APs have had considerable impact as tools of clinical investigation and intervention. One particular example is tartrate resistant acid phosphatase, which is detected in the serum in raised amounts accompanying pathological bone resorption. This article seeks to explore the identity and diversity of APs, and to demonstrate the relation between APs, human disease, and clinical diagnosis.

The role of external radiotherapy in patients treated with permanent prostate brachytherapy

To examine the difference in Prostate Specific Antigen (PSA)-Relapse Free Survival (RFS) in patients (pts) with prostate cancer treated with permanent prostate brachytherapy (PPB) alone (monotherapy) or combined modality PPB and external radiotherapy (CMT) by a matched pair analysis. There were 1476 pts who were treated loosely based on the American Brachytherapy Society criteria for monotherapy or CMT. PSA-RFS was based upon the Kattan modification of the ASTRO consensus panel definition. A computer generated matching process was undertaken to produce two equally weighted pairs of patients divided by treatment methodology and Kaplan-Meier PSA-RFS curves were generated and compared by chi(2) testing. All pts were treated between 1992 and 2000 with a 6-y PSA-RFS of 81.9%. The median follow-up was 34.7 months. Patients treated with CMT presented with higher pre-treatment PSA values, Gleason sum score, clinical stage, risk classification, and were more likely to be treated with neoadjuvant hormones. A matched-pair analysis with 314 pts in each group was created stratified by the addition of neoadjuvant hormones, Gleason score sum and the pretreatment PSA value. Actuarial 5-y PSA-RFS was 77.0% for the monotherapy group and 81.1% for the combined therapy group (P=0.54).chi(2) testing by pretreatment PSA value, Gleason score sum, risk stratification, isotope and the addition of neoadjuvant hormones failed to identify any group with a significant difference in 5-y PSA-RFS. In conclusion, this retrospective study presents a large cohort of patients treated with PPB that failed to identify a significant advantage for the addition of combined therapy. A matched pair analysis performed also failed to identify any significant difference based on treatment modality.

Relationship between percent positive biopsies and biochemical outcome after permanent interstitial brachytherapy for clinically organ-confined carcinoma of the prostate gland

PURPOSE

Recently, the percentage of positive prostate biopsies has been reported to be statistically significant in predicting the biochemical outcome after either radical prostatectomy or 3-dimensional conformal external beam radiotherapy. In this study, we evaluated the impact of the percentage of positive prostate biopsies in predicting the 5-year biochemical outcome for patients with clinically organ-confined prostate cancer undergoing permanent interstitial brachytherapy.

METHODS AND MATERIALS

Two hundred sixty-two hormone naive patients underwent transperineal ultrasound-guided permanent prostate brachytherapy with generous periprostatic margins, using either 103Pd or 125I for clinical T1b/T2b NXM0 (1997 AJCC) adenocarcinoma of the prostate gland from April 1995 to October 1999. No patient was lost to follow-up. The actual percentage of positive biopsies (number of positive biopsies/total number of biopsies) was determinable for 255 of the 262 patients. Of the evaluated cases, 133 patients were implanted with 103Pd and 122 patients with 125I. The median patient age was 68 years (range 48-81). The median follow-up was 38.6 months (range 6-73). Follow-up was calculated from the day of implantation. Patients were stratified by the percentage of positive biopsies into the following groups: <34%, 34-50%, and >50%. Additional clinical parameters evaluated included patient age, clinical T-stage, Gleason score, pretreatment prostate specific antigen (PSA), risk group, and prostate volume. Low-risk patients were staged as clinical T1c/T2a, Gleason score < or =6, and pretreatment PSA < or =10 ng/mL, intermediate-risk patients presented with one unfavorable prognostic parameter, and high-risk patients presented with two or more unfavorable prognostic parameters (clinical stage T2b, PSA >10 ng/mL, Gleason score > or =7). Treatment parameters included the use of supplemental external beam radiation and choice of isotope. Biochemical disease-free survival was defined by the American Society of Therapeutic Radiation and Oncology consensus definition.

RESULTS

For the 255 evaluated patients, the 5-year actuarial biochemical no evidence of disease survival rate was 92.5%. For patients with low, intermediate, and high-risk disease, 95.8%, 98.1%, and 79.4% of patients were free of biochemical failure, respectively. When each risk group was stratified into the percent positive biopsy categories of <34%, 34-50%, and >50%, no statistical difference was found in biochemical outcome for the biopsy subgroups. In multivariate analysis, none of the clinical or treatment parameters predicted for failure in the low-risk group; only Gleason score was predictive for intermediate-risk patients and only PSA for high-risk patients. In the overall population, PSA and Gleason score were both found to be predictors of biochemical failure, but not risk group, clinical stage, or percentage of positive biopsies. There was no significant dependence between the percent positive biopsy group and the Kaplan-Meier biochemical survival rates for any of the various subgroups of clinical and treatment parameters, except for clinical stage T1c-T2a (p = 0.006). The median postimplant PSA was 0.2 ng/mL for patients with either low-risk disease or <34% positive biopsies and 0.1 ng/mL for all other risk groups or percent positive biopsy subgroups.

CONCLUSION

Although a significant trend was found for biochemical failure with increasing percent positive biopsies in the overall population, our results suggest that the percentage of positive biopsies is not statistically significant in predicting the 5-year biochemical disease-free outcome for patients with low, intermediate, and high-risk disease undergoing permanent prostate brachytherapy. Only the Gleason score in intermediate-risk patients and the pretreatment PSA level in high-risk patients was predictive of biochemical failure. We believe this relative lack of significance for the percentage of positive biopsies is a result of dose escalation far exceeding other radiotherapy modalities and the ability to aggressively treat the periprostatic region compared with radical prostatectomy by way of the accurate placement of periprostatic seeds.

Biochemical outcome for hormone-naı̈ve intermediate-risk prostate cancer managed with permanent interstitial brachytherapy and supplemental external beam radiation

PURPOSE

To report the 6-year biochemical disease-free outcome for hormone-naïve patients with intermediate-risk disease (Gleason score > or =7, prostate-specific antigen (PSA) > or =10 ng/ml, or clinical stage > or =T2b [1997 American Joint Committee on Cancer]) undergoing brachytherapy with supplemental external beam radiation (XRT).

METHODS AND MATERIALS

Seventy-seven consecutive hormone-naïve intermediate-risk prostate cancer patients received supplemental XRT followed by a brachytherapy boost. No patient underwent pathologic lymph node staging. The median patient age was 69 years and the median follow-up was 52 months. Biochemical disease-free survival was defined by the American Society of Therapeutic Radiology and Oncology consensus definition. Clinical and treatment parameters evaluated included patient age, clinical stage, Gleason score, pretreatment PSA, and isotope.

RESULTS

The 6-year actuarial biochemical no-evidence-of-disease survival rate was 97.4%. None of the evaluated clinical or treatment parameters, except for a Gleason score > or =8, predicted for failure. The mean and median posttreatment PSA was 0.08 +/- 0.19 ng/ml and <0.1 ng/ml, respectively. When stratified by isotope, the mean posttreatment PSA was not significantly different (0.07 +/- 0.11 ng/ml for 103Pd vs. 0.14 +/- 0.32 ng/ml for 125I; p=0.397).

CONCLUSIONS

Hormone-naïve intermediate-risk prostate cancer patients undergoing brachytherapy with supplemental XRT have a high probability of 6-year biochemical disease-free survival. None of the evaluated clinical or treatment parameters, except Gleason score > or =8, predicted for treatment failure.

I-125 versus Pd-103 for low-risk prostate cancer: morbidity outcomes from a prospective randomized multicenter trial

PURPOSE

The purpose of this study was to test the hypothesis that the shorter half-life of Pd-103 versus I-125 results in a shorter duration of radiation-related symptoms after prostate brachytherapy.

METHODS

As of February 2000, 110 of a planned total of 380 patients with 1997 American Joint Commission clinical stage T1c-T2a prostatic carcinoma (Gleason grade 2-6, prostate-specific antigen, 4-10 ng/mL) had been randomly assigned to implantation with I-125 (144 Gy, TG-43) or Pd-103 (125 Gy, NIST-99). Isotope implantation was performed by standard techniques, using a modified peripheral loading pattern. Treatment-related morbidity was monitored by mailed questionnaires, using standard American Urologic Association (AUA) and Radiation Therapy Oncology Group criteria at 1, 3, 6, 12, and 24 months. Use of alpha-blockers to relieve obstructive symptoms was not controlled for but was noted at each follow-up point. All patients reported here have a minimum 1-year follow-up. Randomization was carried out at a central enrollment office where eligibility criteria were confirmed and the patient assigned by computerized random number generator to one of the two treatment arms. Patients were assigned to 95 blocks of four. Most statistical comparisons shown here are by Student's unpaired t-test at specific follow-up times, as indicated in the figure legends. Additionally, considering the patients' scores change overtime, repeated measures were incorporated in a mixed model assuming an unstructured covariance matrix.

RESULTS

Patients in each arm were well matched by preimplant prostate volume, AUA score, and age. The AUA scores peaked at the 1-month point for both isotopes and then gradually declined. The difference was greatest at 6 months, when I-125 patients had a mean AUA score of 16 (+/- 8), compared with 11 (+/- 10) for the Pd-103 patients. By 12 months, mean AUA scores for the Pd-103 patients had decreased to 12 (+/- 9), compared with 13 (+/- 8) for the I-125 patients. At 6 months after implantation, 41% of Pd-103 patients were still taking alpha-blockers, versus 44% of I-125 patients. The differences between isotopes were more marked in patients with a low pretreatment AUA score or smaller preimplant transrectal ultrasonography volume. Results of the mixed model, incorporating repeated measures for each patient, showed that the effect of isotope choice on AUA score depended on time. This effect was further dependent on baseline AUA score, but not on transrectal ultrasonography volume or on age. Urinary and rectal morbidity was generally low, typically grade 1 or 2. There was a trend to greater morbidity with I-125 than with Pd-103, most markedly at the 6-month time point.

DISCUSSION

Patients treated with Pd-103 recovered from their radiation-induced prostatitis sooner than I-125 patients. It appears that patients with minimal pretreatment urinary obstructive symptoms are the most likely to experience implant-related exacerbations of their symptoms and are the most likely to benefit from the more rapid half-life of Pd-103 rather than I-125.

Pretreatment nomogram for predicting freedom from recurrence after permanent prostate brachytherapy in prostate cancer

OBJECTIVES

To develop a prognostic nomogram to predict the freedom from recurrence for patients treated with permanent prostate brachytherapy for localized prostate cancer.

METHODS

We performed a retrospective analysis of 920 patients treated with permanent prostate brachytherapy between 1992 and 2000. The clinical parameters included clinical stage, biopsy Gleason sum, pretreatment prostate-specific antigen (PSA) value, and administration of external beam radiation. Patients who received neoadjuvant androgen deprivation therapy were excluded. Failure was defined as any post-treatment administration of androgen deprivation, clinical relapse, or biochemical failure, defined as three PSA rises. Patients with fewer than three PSA rises were censored at the time of the first PSA rise. Data from two outside institutions served as validation.

RESULTS

A nomogram that predicts the probability of remaining free from biochemical recurrence for 5 years after brachytherapy without adjuvant hormonal therapy was developed using Cox proportional hazards regression analysis. External validation revealed a concordance index of 0.61 to 0.64, and calibration of the nomogram suggested confidence limits of +5% to -30%.

CONCLUSIONS

The pretreatment nomogram we developed may be useful to physicians and patients in estimating the probability of successful treatment 5 years after brachytherapy for clinically localized prostate cancer.

Five-year biochemical outcome following permanent interstitial brachytherapy for clinical T1-T3 prostate cancer

PURPOSE

To evaluate 5-year biochemical disease-free outcome for men with clinical T1b-T3a NxM0 1977 American Joint Committee on Cancer (1997 AJCC) adenocarcinoma of the prostate gland who underwent transperineal ultrasound-guided permanent prostate brachytherapy.

METHODS AND MATERIALS

Four hundred twenty-five patients underwent transperineal ultrasound-guided prostate brachytherapy using either 103Pd or 125I, for clinical T1b-T3a NxM0 (1997 AJCC) adenocarcinoma of the prostate gland, from April 1995 to October 1999. No patient underwent pathologic lymph-node staging. One hundred ninety patients were implanted with either 103Pd or 125I monotherapy; 235 patients received moderate-dose external beam radiation therapy (EBRT), followed by a prostate brachytherapy boost; 163 patients received neoadjuvant hormonal manipulation, in conjunction with either 103Pd or 125I monotherapy (77 patients) or in conjunction with moderate-dose EBRT and a prostate brachytherapy boost (86 patients). The median patient age was 68.0 years (range, 48.2-81.3 years). The median follow-up was 31 months (range, 11-69 months). Follow-up was calculated from the day of implantation. No patient was lost to follow-up. Biochemical disease-free survival was defined by the American Society of Therapeutic Radiation and Oncology (ASTRO) consensus definition.

RESULTS

For the entire cohort, the 5-year actuarial biochemical no evidence of disease (bNED) survival rate was 94%. For patients with low-, intermediate-, and high-risk disease, the 5-year biochemical disease-free rates were 97.1%, 97.5%, and 84.4%, respectively. For hormone-naive patients, 95.7%, 96.4%, and 79.9% of patients with low-, intermediate-, and high-risk disease were free of biochemical failure. Clinical and treatment parameters predictive of biochemical outcome included: clinical stage, pretreatment prostate-specific antigen (PSA), Gleason score, risk group, age > 65 years, and neoadjuvant hormonal therapy. Isotope choice was not a statistically significant predictor of disease-free survival for any risk group. The median postimplant PSA was < or = 0.2 for all risk groups, regardless of hormonal status. The mean posttreatment PSA, however, was significantly lower for men implanted with 103Pd (0.14 ng/mL) than for those implanted with 125I (0.25 ng/mL), p < or = 0.001.

CONCLUSION

With a median follow-up of 31 months, permanent prostate brachytherapy results in a high probability of actuarial 5-year biochemical disease-free survival (DFS) for patients with clinical T1b-T3a (1997 AJCC) adenocarcinoma of the prostate gland, with an apparent plateau on the PSA survival curve.

Five-year biochemical outcome after prostate brachytherapy for hormone-naive men < or = 62 years of age

PURPOSE

To evaluate 5-year biochemical disease-free outcome for hormone naïve men 62 years of age or less who underwent transperineal ultrasound-guided permanent prostate brachytherapy.

METHODS AND MATERIALS

76 patients underwent transperineal ultrasound guided prostate brachytherapy using either (103)Pd or (125)I for clinical T1b--T2b NxM0 (1997 AJCC) adenocarcinoma of the prostate gland from April 1995 to October 1999. No patient was lost to follow-up, and no patient underwent pathologic lymph-node staging. 47 patients were implanted with either (103)Pd or (125)I monotherapy, and 29 patients received moderate-dose external-beam radiation therapy followed by a prostate brachytherapy boost. No patient received hormonal manipulation. The median patient age was 58 years (range, 48--62 years). The median follow-up was 37 months (range, 14--70 months). Follow-up was calculated from the day of implantation. Biochemical disease-free survival was defined by the American Society of Therapeutic Radiation and Oncology (ASTRO) consensus definition.

RESULTS

The actuarial 5-year biochemical disease-free survival rate was 98.7%. For patients with low-, intermediate-, and high-risk disease, 97.7%, 100%, and 100%, respectively, were free of biochemical failure. The median posttreatment prostate-specific antigen (PSA) for the entire group was 0.2 ng/mL. When stratified by risk group, the median posttreatment PSA was 0.2, 0.15, and 0.1 for patients with low-, intermediate-, and high-risk disease, respectively.

CONCLUSION

With a median follow-up of 37 months, hormone naïve patients < or = 62 years of age have a high probability of 5-year biochemical disease-free survival following permanent prostate brachytherapy with an apparent plateau on the PSA curve.

A comprehensive review of CT-based dosimetry parameters and biochemical control in patients treated with permanent prostate brachytherapy

PURPOSE

The American Brachytherapy Society recommends that postprostate implant dosimetry be performed on all patients undergoing transperineal interstitial permanent prostate brachytherapy (TIPPB) utilizing CT scan clinical target volume reconstructions. This study was undertaken to assess the recommended dosimetry parameters from a large cohort of patients undergoing TIPPB that would predict for PSA relapse-free survival (PSA-RFS).

METHODS AND MATERIALS

Seven hundred nineteen consecutive patients with clinical stage T1/T2 adenocarcinoma of the prostate underwent TIPPB using either I-125 or Pd-103. Postimplant dosimetry was performed at 2 to 3 weeks with CT scan 3-dimensional reconstructions obtained on all patients. The D90 and D100 doses (defined as the minimum dose covering 90% and 100% of the prostate volume, respectively) and the V100 (defined as the percent of the prostate receiving 100% of the prescribed dose) were obtained for each patient. Regression analysis was performed on the D90 dose, D100 dose, and V100 to test for cutoff points that would predict for PSA-RFS, defined by a modification of the American Society for Therapeutic Radiology and Oncology consensus panel statement. A cutoff value was found and was subjected to subset analysis to assess for its robustness. Treatment-related factors were tested for their ability to achieve dosimetry at or above the cutoff dose.

RESULTS

The median follow-up from this cohort is 30 months (7-71 months) with a 48-month PSA-RFS of 89.5%. A D90 dose-response cutoff value > or =90% of the prescribed dose was identified. Prostate implants with a D90 dose <90% of the prescribed dose had an 80.4% 4-year PSA-RFS, while those with a D90 dose > or =90% of the prescribed dose had a 92.4% 4-year PSA-RFS (p = 0.001). No cutoff value was found for the V100 and D100 dose that predicted for PSA-RFS. Using the cutoff value, the D90 dose at 90% of the prescribed dose, a difference in 4-year PSA-RFS survival was identified for patients treated with I-125 (p = 0.04), Pd-103 (p = 0.01), TIPPB as monotherapy (p = 0.001), the addition of hormone therapy (p = 0.005), and TIPPB without hormone therapy (p = 0.001). The D90 dose was not significant for the group of patients treated with external beam radiotherapy and TIPPB (p = 0.15). The only significant finding from Cox regression analysis to predict for a poor D90 dose (<90% of the prescribed dose) was a CT/TRUS volume ratio >1.5 (p = 0.02).

CONCLUSIONS

The American Brachytherapy Society recommends that postimplant CT-based dosimetry be performed for all patients treated with TIPPB. This prospective study identified that the D90 dose > or =90% of the prescribed dose can be used as a factor for predicting PSA-RFS in patients treated with brachytherapy. A dose-response using the D90 dose was observed for several typical clinical treatment variations used in the practice of TIPPB. Using the D90 dose appears to be a satisfactory parameter for predicting outcome in patients treated with TIPPB.

IMPROVED OUTCOMES WITH RADIATION FOR PROSTATE CANCER

During the last 15 years, a series of substantial technical improvements have occurred in external beam radiation and brachytherapy. The introduction of PSA-based posttreatment monitoring has allowed a reasonable comparison between each radiation modality and prostatectomy. Such comparisons show more similarities than differences. Probably the most exciting finding in regard to curing cancer is that higher-risk patients have a more favorable prognosis than previously recognized using higher doses now achievable with either form of radiation.

Comparison of dose length, area, and volume histograms as quantifiers of urethral dose in prostate brachytherapy

PURPOSE

To determine the magnitude of the differences between urethral dose-volume, dose-area, and dose-length histograms (DVH, DAH, and DLH, respectively, or DgH generically).

METHODS AND MATERIALS

Six consecutive iodine-125 ((125)I) patients and 6 consecutive palladium-103 ((103)Pd) patients implanted via a modified uniform planning approach were evaluated with day 0 computed tomography (CT)-based dosimetry. The urethra was identified by the presence of a urinary catheter and was hand drawn on the CT images with a mean radius of 3.3 +/- 0.7 mm. A 0.1-mm calculation matrix was employed for the urethral volume and surface analysis, and urethral dose points were placed at the centroid of the urethra on each 5-mm CT slice.

RESULTS

Although individual patient DLHs were step-like, due to the sparseness of the data points, the composite urethral DLH, DAH, and DVHs were qualitatively similar. The DAH curve delivered more radiation than the other two curves at all doses greater than 90% of the prescribed minimum peripheral dose (mPD) to the prostate. In addition, the DVH curve was consistently higher than the DLH curve at most points throughout that range. Differences between the DgH curves were analyzed by integrating the difference curves between 0 and 200% of the mPD. The area-length, area-volume, and volume-length difference curves integrated in the ratio of 3:2:1. The differences were most pronounced near the inflection point of the DgH curves with mean A(125), V(125), and L(125) values of 36.6%, 31.4%, and 23.0%, respectively, of the urethra. Quantifiers of urethral hot spots such as D(10), defined as the minimal dose delivered to the hottest 10% of the urethra, followed the same ranking: area analysis indicated the highest dose and length analysis, the lowest dose. D(10) was 148% and 136% of mPD for area and length evaluations, respectively. Comparing the two isotopes in terms of the amount of urethra receiving a given dose, (103)Pd implants were significantly cooler than (125)I implants over most of the range of clinical interest, from 100% to 150% of mPD.

CONCLUSION

Dose gradients in prostate implants result in the observed ordering of DAH, DVH, and DLH from higher to lower doses. The three histogram approaches remain in close agreement up to 100% of the mPD but diverge at higher doses. Although urethral point doses are the most easily determined, they underestimate the amount of urethra at risk at higher doses compared to dose area analysis. Because dosimetric parameters detailing high-dose regions such as D(10) show only slight differences between calculation methods, they are recommended over the corresponding geometric entities G(150) or G(175). The differences between the D(gg) entities are sufficiently small that they are unlikely to be of clinical significance or to confound analyses attempting to correlate urinary morbidity with urethral dosimetry.

Rectal function following prostate brachytherapy

PURPOSE

Quality of life following therapeutic intervention for carcinoma of the prostate gland has not been well documented. In particular, a paucity of data has been published regarding bowel function following prostate brachytherapy. This study evaluated late bowel function in 209 consecutive prostate brachytherapy patients via a one-time questionnaire administered 16-55 months postimplant.

MATERIALS AND METHODS

Two hundred nineteen consecutive patients underwent permanent prostate brachytherapy from April 1995 through February 1998 using either (125)I or (103)Pd for clinical T1c-T3a carcinoma of the prostate gland. Of the 219 patients, 7 had expired. Of the remaining 212 patients (median follow-up, 28 months), each patient was mailed a self-administered questionnaire (10 questions) with a prestamped return envelope; 209 (98.6%) surveys were returned. Clinical parameters evaluated for bowel dysfunction included patient age, diabetes, hypertension, history of tobacco consumption, clinical T-stage, elapsed time since implant, and prostate ultrasound volume. Treatment parameters included utilization of neoadjuvant hormonal manipulation, utilization of moderate dose external beam radiation therapy prior to implantation, choice of isotope ((125)I vs. (103)Pd), rectal dose (average, median and maximum doses), total implanted seed strength, values of the minimum dose received by 90% of the prostate gland (D(90)), and the percent prostate volume receiving 100%, 150%, and 200% of the prescribed minimum peripheral dose (V(100), V(150) and V(200), respectively). Because detailed baseline bowel function was not available for these patients, a cross-sectional survey was performed in which 30 newly diagnosed prostate cancer patients of comparable demographics served as controls.

RESULTS

The total rectal function scores for the brachytherapy and control patients were 4.3 and 1.6, respectively, out of a total 27 points (p < 0.001). Of the evaluated clinical parameters, only the preimplant number of bowel movements per day were correlated with the total survey score (p < 0.01). None of the treatment parameters were significantly correlated with the total survey score. Despite the fact that implantation with (103)Pd resulted in lower radiation doses to the rectum, the choice of isotope was not predictive of bowel function scores. A trend toward increased rectal scores was noted for older patients, and a nonsignificant improvement in rectal survey scores was noted with elapsed time from implantation. Only 19.2% (40/208) of the treatment group reported a worsening of bowel function following implantation. Patient perception of overall rectal quality of life, however, was inversely related to the utilization of external beam radiation therapy (p = 0.034).

CONCLUSION

To date, no severe changes in late bowel function have been noted following prostate brachytherapy. Although the survey scores indicate bowel function is worse after an implant, the minor changes are not significant enough to bother most individuals. Less than 20% of patients reported that their bowel function was worse following prostate brachytherapy.

American brachytherapy society recommendations for clinical implementation of NIST-1999 standards for (103)palladium brachytherapy. The clinical research committee of the American Brachytherapy Society

PURPOSE

Recent important developments in palladium-103 ((103)Pd) dosimetry mandate a reevaluation of (103)Pd brachytherapy prescribing practices.

METHODS AND MATERIALS

The clinical research committee of the American Brachytherapy Society (ABS) convened a consensus session of brachytherapists and physicists to develop recommendations regarding future dose prescribing guidelines for National Institute of Standards and Technology (NIST-1999) calibrated (103)Pd sources.

RESULTS

The ABS recommends that clinicians attempt to reproduce the implant doses delivered and reported in the literature through the past decade.

CONCLUSIONS

The following should be immediately implemented for (103)Pd dosimetry: 1) All practicing physicians, physicists, dosimetrists, and suppliers implement NIST-1999 air-kerma strength standard for (103)Pd brachytherapy. 2) All treatment planning systems and dose calculation algorithms must be updated to reflect new dose rate constants. The AAPM-recommended validated value for Theraseed model 200 is 0.665 cGy h(-1) U(-1). The dose rate constant for the Mentor MED3633 seed is currently reported as 0.68 cGy h(-1) U(-1). This latter value and the values for seeds from other manufacturers are awaiting independent confirmation. 3) Physicians who previously prescribed 115 Gy for (103)Pd monotherapy prostate implants should now prescribe 125 Gy. When using (103)Pd as a boost following 45 Gy of external beam irradiation, 100 Gy should be prescribed instead of the previous 90 Gy. It is critical that all three changes be implemented concurrently, because they are interdependent.